The present invention relates to an automatic film developing apparatus, and more particularly to an apparatus for treating exposed sensitized papers or photographic films continuously and full-automatically by the steps of development, fixing, washing with water and drying in sequence.
The developer for such a film developing apparatus progressively deteriorates or ages when used for developing films. The aging of the developer is caused by the film developing treatment or by oxidation which occurs when the developer is allowed to stand. When the developer ages owing to either of these causes, the oxidation reduction potential (hereinafter referred to as "ORP") drops. Accordingly, the degree of aging of the developer can be detected by measuring the ORP of the developer.
The aging of the developer gives an obscure finish to the developed film. If exposed films are developed with a developer which has aged beyond a limit, distinct images will not be obtained, with the likelihood that the subsequent treatment will involve a serious error. Such a failure is readily avoidable by following the required measures, such as replenishment of the developer, if the ORP value is detectable in advance. Furthermore when the degree of aging is within the limit, films can be developed to give clear images by adjusting the developing speed to a value in accordance with the degree of aging.